Let's talk about 6m FM

[902]

I think that if you removed the duplexers from the equation, setting up a low band repeater system wouldn't be a big deal if you could find a central transmitter site and several receiver sites which could be remoted with "poor man's microwave" (UHF links). I'm thinking you work on the NTIA side of the house, so maybe a few horizontally polarized A-band links bringing status tone and receive audio back to a voting comparator and a decent transmitter would be a very reliable wide-area system. And, for close-in, a receiver closer to the ground with adequate vertical and spectral separation without ever needing a duplexer. Those things are just unwieldy at 40 MHz - like stringing water heaters together. One police department near where I lived 25 years ago used duplexers on 39 MHz and it occupied much of their radio area.

Just after I moved and took a job in the Midwest, my employer (a consortium of public sector agencies) was embroiled in battle royale style politics with county government for who had control. As VHF high band was at a premium and was warehoused by a number of agencies who had a Monday channel, a Tuesday channel, a channel for this, a channel for that, etc. all on a first-come first-served basis, the only option I saw was low band. I had licensed a 33 MHz frequency for a repeater output and the next adjacent, 20 kHz away, for the input. There was also a 33 MHz fireground channel. I had sites, and I had surplus equipment (a Motrac Compa base). I put up a DB-201 at the transmit site, had a GE comparator, and a few voting receivers that I swapped boards to put on the 33 MHz input. They were fed into existing leased circuits we already had for another project. Faith and Begorrah, the thing worked marvelously. I had more than adequate isolation with 10 or so miles between transmit and receive sites, even at 20 kHz separation. I had a few Maxar 80 mobiles crystalled up for it, and it beat what we were using on high band at the time. As fate would have it, it never was put into play and was actually dismantled shortly before all of the consortium employees were laid off in the transition. Gotta love it. But as a proof of concept, it's certainly doable, and it could be done for very little. Granted, that was in 1997 when much of this stuff was still floating around. I haven't seen a low band Micor T81 chassis on the auction sites in ages, and don't particularly care for the lite duty stuff that's out there now.

My old 6 meter repeater was made out of some old PennDOT RCA 1000 radios that were modded to be in spec on 6. I may have one left that's on 52.525, but I'll be darned if I know where the cable, control head, and mic are for it anymore.

 

[KD8DVR]

Hey Token...I agree....while the practical, budget watching, effort-miserly little me says to the low band repeaters..."Why ??!!"
the Ham in me says-- "Why Not!?"
Heck, now you've all started me thinking, ....maybe we'll try out something simple in the way of a low band repeater... Maybe.......something *simple*........Maybe....Hmmmmm.........I know where there's a set of cavities sitting just looking for a mission..................................................................
.
You all aren't holding your breaths I hope.... ! (lol !)

........................CF

My thoughts exactly. When people ask me what the point of ham radio is, I say, "there is none". Sometimes, we just wanna play, because we can.

Sent from my LG-D631 using Tapatalk

 

[prcguy]

Portable 6m repeater anyone? Here is my do anything setup and I've tested it as a portable 6m repeater using a very wide split with a field tunable military duplexer and also as a 220 and 440 to 6m cross band repeater.

The controller will take in up to 5 radios and one can be a cell phone plus it has a landline input. It has two separate busses where you can have two radios as a seperate 6m repeater and the other two as a seperate 2m or 220 or 440 repeater and with the flip of a switch have them criss-cross band or anything in between.

The radios do any freq from 30 to 512MHz and the 40w amps cover the same range with internal auto sensed and switched narrow band pass filters. I have portable duplexers for 2m, 220 and 440 but no narrow spaced 6m duplexer yet. A set of full size cans for 6m probably won't be considered portable at that point.
prcguy

I think that if you removed the duplexers from the equation, setting up a low band repeater system wouldn't be a big deal if you could find a central transmitter site and several receiver sites which could be remoted with "poor man's microwave" (UHF links). I'm thinking you work on the NTIA side of the house, so maybe a few horizontally polarized A-band links bringing status tone and receive audio back to a voting comparator and a decent transmitter would be a very reliable wide-area system. And, for close-in, a receiver closer to the ground with adequate vertical and spectral separation without ever needing a duplexer. Those things are just unwieldy at 40 MHz - like stringing water heaters together. One police department near where I lived 25 years ago used duplexers on 39 MHz and it occupied much of their radio area.

Just after I moved and took a job in the Midwest, my employer (a consortium of public sector agencies) was embroiled in battle royale style politics with county government for who had control. As VHF high band was at a premium and was warehoused by a number of agencies who had a Monday channel, a Tuesday channel, a channel for this, a channel for that, etc. all on a first-come first-served basis, the only option I saw was low band. I had licensed a 33 MHz frequency for a repeater output and the next adjacent, 20 kHz away, for the input. There was also a 33 MHz fireground channel. I had sites, and I had surplus equipment (a Motrac Compa base). I put up a DB-201 at the transmit site, had a GE comparator, and a few voting receivers that I swapped boards to put on the 33 MHz input. They were fed into existing leased circuits we already had for another project. Faith and Begorrah, the thing worked marvelously. I had more than adequate isolation with 10 or so miles between transmit and receive sites, even at 20 kHz separation. I had a few Maxar 80 mobiles crystalled up for it, and it beat what we were using on high band at the time. As fate would have it, it never was put into play and was actually dismantled shortly before all of the consortium employees were laid off in the transition. Gotta love it. But as a proof of concept, it's certainly doable, and it could be done for very little. Granted, that was in 1997 when much of this stuff was still floating around. I haven't seen a low band Micor T81 chassis on the auction sites in ages, and don't particularly care for the lite duty stuff that's out there now.

My old 6 meter repeater was made out of some old PennDOT RCA 1000 radios that were modded to be in spec on 6. I may have one left that's on 52.525, but I'll be darned if I know where the cable, control head, and mic are for it anymore.

 

[902]

OH! No fair pulling out those MBITRs!

That has to be the coolest thing I've seen in a long time, radio-wise, by far!

 

[prcguy]

Ok, back in the closet with them. I forgot to mention it also works great with an HF radio patched in. The later Harris HF rigs are all DSP based and have syllabic squelch, which works perfectly with the repeater controller. And all these rigs have the same handset connector so its just plug and play then select the freqs you want to run. Most of the time this stuff just sits around as a solution waiting for a need.
prcguy

OH! No fair pulling out those MBITRs!

That has to be the coolest thing I've seen in a long time, radio-wise, by far!

 

[902]

Ok, back in the closet with them. I forgot to mention it also works great with an HF radio patched in. The later Harris HF rigs are all DSP based and have syllabic squelch, which works perfectly with the repeater controller. And all these rigs have the same handset connector so its just plug and play then select the freqs you want to run. Most of the time this stuff just sits around as a solution waiting for a need.
prcguy

One of these days when I'm out your way, I would love to see what kind of collection you have! I played with matrixing systems using JPS boxes and was not impressed. There were too many delays, see-saws, and quirks that never could assure the message went through. What you described sounds like it's what a JPS box and associated "stuff" wanted to be when it grew up.

 

[kayn1n32008]

Ok, back in the closet with them. I forgot to mention it also works great with an HF radio patched in. The later Harris HF rigs are all DSP based and have syllabic squelch, which works perfectly with the repeater controller. And all these rigs have the same handset connector so its just plug and play then select the freqs you want to run. Most of the time this stuff just sits around as a solution waiting for a need.
prcguy

Codan has a system that can use HF radios to link multiple analogue/P25 repeaters together. Even securely, where the HF link is encrypted.

https://www.codanradio.com/product/mray/

Edit: Quoted 902 instead of prcguy.

 

[prcguy]

I've never played with a JPS box and this one is made by Communications-Applied Technology or C-AT. Its pretty elaborate inside and the VOX works really well. You can also plug in a military handset and assign to any bus for monitoring or local control. It was an Ebay find out of the UK for $100 plus shipping.

Back to the 6m thing, in my local group of friends we have a GE Master II repeater in the 48MHz range and another guy has some misc low band cans and I've got several 6m antennas and we have several mountain top repeater sites with space. The only thing we really need is a coordinated pair and there could be yet another So Cal 6m repeater on the air. I think it wold be nifty to use 150Hz tone so all the people with surplus PRC-25's 77's and so on could get them on the air through a repeater.
prcguy

One of these days when I'm out your way, I would love to see what kind of collection you have! I played with matrixing systems using JPS boxes and was not impressed. There were too many delays, see-saws, and quirks that never could assure the message went through. What you described sounds like it's what a JPS box and associated "stuff" wanted to be when it grew up.

 

[N5TWB]

I think that if you removed the duplexers from the equation, setting up a low band repeater system wouldn't be a big deal if you could find a central transmitter site and several receiver sites which could be remoted with "poor man's microwave" (UHF links).

Our club just re-established our 6m repeater at a single-site so had to use cans. OMG, those things are HUGE...and pricey, too! Luckily, space was not at a premium as the re-purposed old Moto low-band cabinet was able to hold all three repeaters (6m, 2m, & 220) so the recovered floor space was taken over by the cans. I certainly now better understand the attraction of using "air duplexers" for this.

The antenna is a re-cut DB-201. Wow, those things are narrow-banded.

 

[SCPD]

Hey Guys....
I bow to your experiences and expertise. The system you set up 902 sounded like it was very impressive, especially considering the technology at the time; a nice piece of work.
.
Fridays are our usual short office meeting days, and I floated the low band repeater idea before some of our Tech's...(they have to endure me, but I buy lunch.) But before I did that, I visited our 'Museum"-- a storage building where old projects go to retire-- they never really die, they just end up in the 'Museum"-- one glorious, huge junk box, actually. And in there were six of the biggest duplexing- duplexers I have ever seen.... Water Heaters describes them perfectly-- older than I am, each beautifully constructed of thick, heavy, silver'd brass-- they must have cost a fortune. There were plates on them, engraved with the frequency they where tuned to-- the low part of 30 Mhz,....hmmmm.. something I could use.....now, if I could only budge them.
So, back to the meeting......I mentioned them, seeing if I could get any reaction- and, Oh.. did I!
.
"Lauri, we don't have the time and YOU don't have the budget to play with those dinosaurs"
"Besides, where would you put such a system?"...
.
They were right, everything here is all digital data sharing, 'phones, tablets..... and away from here where we do our stuff its Nothing....the problem is, that 'Nothing' is the entire lower half of New Mexico, all of Nevada.... where could such a system be placed where we'd have a chance of ever using it?
.
"I'll tell you what" said one of the guys that know this stuff " we have an unused 250 Watt GE base on 41 Mhz. No one wants its. What I will do is make it into a Simplex Repeater for your Fall Project. When we go out to install that equipment I will see it gets put on one of the tallest site and you can play around with it to your heart's content" (this will be in Nevada-- a vast place where our mobiles often fall into radio" holes.")
.
A Simplex Repeater !...what's called a Parrot, No?...... Smashing!
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The duplexers in the 'museum' can sit there for another 50 years... stay tuned -- see how this turns out in the Fall
.
And a big *Thank you all* for your ideas !

..................................................CF

 

[bill4long]

Most of the 6m activity in the midwest and east USA is on JT65/9 now and USB. A little CW. Contacts up to 600 miles are common when E skip is open. Otherwise deads-ville. We've had a fair amount of E skip in the past few weeks. T'is the time of year for it. In a month it will be dead again until next summer.

There are a few 6m repeaters where I live. Been there forever. Nobody uses them.

 

[902]

The system you set up 902 sounded like it was very impressive, especially considering the technology at the time; a nice piece of work.

Lauri, That spectrum-efficient statewide system that was set up in NJ is not mine. It was operated by a fellow named Glenn, and I think he inherited it from someone previous to him. I only set up something simple, but it worked pretty good. He's retired now, so I don't know if the system is continued. My 6 meter systems have been down for a little over 7 years since I vested out of that job and moved to a warmer climate. I've got some Micor and Hamtronics strips in a box buried in the garage.

That parrot concept sounds interesting. What I would do is change the CTCSS for the receiver to make it something different than the transmitter. Then use something like EchoStation for the store-and-forward function. Then program your mobiles and portables for F1 as simplex RF, but in TX, the receive CTCSS at the base, and in RX, the transmit CTCSS at the base. For F2, put the transmit CTCSS of the base into TX and RX for a "talk-around." This represents the least expensive solution. No cans! But you'd need to hear everything. I had one of these up, but hated listening to myself (I think I sound like Bullwinkle, hearing everything I say kicking back to me). But you could have F1 as wide area and F2 as "scene of activity." You'd need an antenna like a DB201 or a DB212 hung on the sides of a tower. If you had a yagi at your lab/office, along with a control station configured like your mobiles and portables, you might be able to hit the "repeater" down range.

 

[SCPD]

I like the separate tone input idea... I too, don't think it makes a Parrot Repeater very popular if you keep hearing all the transmissions twice.
.
I got a few more details on what is planned-- the guys are doing it as a side project, no priority, as a favor to me, so I can expect it sometime "before the snow flies"... but not a whole lot sooner ....
What they planned to do is put that Base station on two on 41Mhz channels. Each channel will have separated Transmit/Receive frequencies, like a regular repeater. This way you don't have to hear a station transmit twice if it is being marginal into the system. I like the idea to use different tones, however, to also achieve this.
.
The guys assure me this should work well, except it will be a 'slow repeater'.... and you have to tolerated hearing yourself with each transmission.... Here I completely agree with you,- I can do without being reminded what I sound like! For that reason this system will be set up separate from our regular operating simplex channels- fearing other team members will get quickly annoyed with hearing themselves being repeated over and over. It will be a back- up system, and if necessary, people can switch over to "Polly One' or "Polly Two" (the names I came up for these two channels
I am not sure what they have in mind for an antenna other than it will be 'impressive' (their words)-
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"When this is up and running it will be really HOT !" (their words-- I like their enthusiasm)
.
Well, we will see.... (smiling) Never did I envision when I got involved in this Post that it would evolve into this (laffing)..... Stay tuned!

....................................CF

 

[902]

"When this is up and running it will be really HOT !" (their words-- I like their enthusiasm)

I love enthusiasm! (It's been a while...)

Good luck!

 

[SCPD]

I am returning to this subject to close out my repeater tale. I was promised a low band "parrot" repeater to use on my last work project- and I received it.... it was installed -- and it worked great! from a Nevada mountain top. I didn't get to see it physically until the project's end; and that was briefly on the day we drove up to its site to remove the simplex recorder and its interface... but I am getting ahead of myself...
.
This simplex, or "parrot' repeater, though not a 6 metre ham setup, mirror'd closely what amateurs can do; so here I list what were its particulars. It was built around an older GE base unit, 1/4Kw from a pair of 4CX250's (?) PA's, feeding a 7/8" run of hardline (left from a previous onsite microwave installation) out and up a 20' tower to what looked like an Olympic pole valulter's fiberglass rod-of-an- antenna-- that antenna must have been 12 to 14 feet in length- a gain antenna, certainly (yes, I know, I should have asked for more details, but we were in haste to get going and had planes to catch, etc.) The input was in a 41Mhz segment, with 40Mhz out.... and with a receive PL tone. The tone part was added as a last minute thought-- not that the input frequency had any other official users,- it doesn't...... but every now and then we get what I call the "Somali Pirates" on these frequencies... not that they they are actual pirates, but they don't speak any language we can make out, and they seem to be on boats (fishing fleets? maybe) - besides Red Sea Pirates radio skip sounds a lot more colourful.......... sorry, I got carried away there.
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From its mountain top location, line-of-sight to other distant mountains was over +60 miles.
.
-------------------And??
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Well. the simplex repeater was a complete success- and yet a dismal failure. It talked crystal clear as far as you could desire... yet---> No one used it.
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If we needed to talk locally, the UHF handhelds worked just fine. If longer distances were required, simplex low band was used mobile to mobile to base. No one, but no one!-- except me --played with that repeater. But I had fun with 'kerchunking" it and listening to myself..... and driving into Las Vegas I was often full quieting over 70-80 miles out.
.
The actual simplex system was simplicity in itself... a solid state interface between the base unit and a 15 (?) year old Radio Shack ham simplex repeater. We took it home, but the now cold (boat anchor) base transceiver awaits a re-awakening on that mountain some day.
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Looking for an interesting 6 metre project...? look no further. Heck, even if you can't find anyone to talk to (like what happened to me ), you can entertain yourself endlessly listening to your own voice!
.
........................................CF

 

[jim202]

I thought we might be able to read something about a real 6 meter repeater. But as usual, you boys let us all down. What a shame. Actually thought someone might come up with some good 6 meter info.

So let me digress and give you some feedback about some actual 6 meter projects. Back years ago, there were some fine radios called Motorola Micor base stations. If you found one in the high split, they could be moved onto 6 meters with some effort. Change a few caps, retune the receiver and change the turns on the PA output coils to work on 6 meters.

I did notice the repeater audio had a good trend toward the highs and few lows. Looked around and changed a couple of the audio coupling caps to 1.0 mfd. That took care of the missing lows and the audio now sounded more normal.

For antennas, we used the folded dipole antennas that were shortened to work on 6 meters. There is a couple of tech documents on the Internet to show you how to modify the antennas. Work great when your done. You just need to knock on the doors of the radio shops to find some of those low band folded dipoles that were used by paging companies and some of the old public safety agencies on low band.

Back about 15 years ago, there was a number of 6 meter repeaters that were active all over the place. even up in Canada. I use to be able to drive over the Causeway bridge over Lake Pontchartrain. that bridge is 24 miles long coming out of Metairie, Louisiana. Would have some good conversations with Canadian stations on my way home almost every day during the summer.

Problem is there are not many active 6 meter repeaters active today. Not sure why they have gone by the wayside. But the activity is just not there anymore. It's a great band that provides some interesting propagation.

I have found that the Motorola Syntor X9000 low band radio works very well on 6 meters with no work at all. It takes more effort to program the radio that any work you have to do with the radio. It uses the same control head that the Spectra radios use. The control cables and power cables are a little scarce, but they can be obtained.

Programming the Syntor X9000 radio is not that hard, but it does take some effort. You do need to make a spread sheet to keep track of the channels (modes) to keep a fixed scan list. Long story between the operator selectable scan and the fixed scan lists. The big thing to remember is the operator scan list goes away when you power down the radio.

Anyway, I have been on my soap box long enough. Time for someone else to chime in.

Jim

 

[k3td]

Six has always been my favorite band, for both FM and SSB/CW. For FM I have a Midland SynTech II mobile and a Yaesu FT-8900. I am puzzled by why local activity seems to be very low, especially when you consider what has happened over the last decade or two -
* Six now included in virtually every current HF rig to help introduce it to more folks
* Lots of commercial FM mobiles at reasonable prices and easy to program/move to 6
* Several VHF/UHF ham mobiles now include 6
* A good supply of 6 meter repeaters and remote bases available - AllStar nodes, etc

The only reason I can think of is the general decline of FM for use while mobile on all VHF/UHF bands, except for weather and public safety nets, etc. I hear very few casual conversations or rag chews on FM on any band.

One idea for how to make it better - AllStar connectivity is now fairly cheap and easy to accomplish, and the linked audio is great even with multiple connections. Any activity encourages more activity, so it may make sense to link 6M machines to other bands as appropriate to generate more chatter.

73,

 

[Token]

I am puzzled by why local activity seems to be very low, especially when you consider what has happened over the last decade or two -

Just my thoughts, opinion, on possibly why the reduction in 6 meter activity...

People experiment less today in voice, non-digital, modes. So 6 is a band that falls by the wayside since the equipment for various digital modes sometimes does not include the band.

Many new users today are appliance operators at first. They buy whatever HT is inexpensive or popular, and that typically does not include 6. They may ask for recommendations, and may be told "6 in an HT is wasted, there is no traffic there". When they get around to buying more gear they often have already established habits, and 6 will not be among those habits.

6 meter hand helds have never been great performers, or large in number. Yeah, this is not really the hardware's fault, more an issue with antenna size. Local activity tends to include HTs, if there are few HTs then there will be less activity.

When the band is not open 6 FM is just as useful as 2 FM for local stuff. But few repeaters and many people ignoring VHF/UHF simplex means that people tend to shun 6 meters. So, fewer repeaters, less traffic, less traffic, less drive for repeaters, etc, a circle that gets tighter and tighter.

T!

 

[SCPD]

I want to amplify some of the excellent points made by Token... and add some of my own, my oh-so salient comments and observations... .... (sarcasm)
I think 6 metre's is to ham radio what low band VHF is to the rest of 2-way radio... 6 is a bypassed dinosaur. There is nothing inherently disadvantageous in using 50 mhz over the other higher vhf/uhf bands--- except that awkward antenna issue. For handheld units you simply can't make them efficient. Anyone remember (or have ever seen, for that matter)- the Motorola low band HT's of years past?..... I do. They had real rubber ducky antennas that measured in feet (sorry, that is an exaggeration- but they seem'd that long to anyone unfortunate enuff to have to carry one..ie: me) And let's not even discuss how (in)efficient they were. Also 6 has remained, except in some very exotic niches, an analog band- the devotees are either vehicle mounted FM mobiles, or fixed home stations on sideband. I know, some really 'out-there' hams will sport high power tropo scatter, meteor reflections- even moon bounce, but for the average ham, what can be done on 6 can be done better on 2/440 if its short ranged, and 10 or below, if its DX. Poor little 6.......
.
Now it wasn't always that way. Back in the "good ole' days"- my father and grandfather were great six metre fans. But in those times there were tonnes of Technican licensees, and 6 was the lowest band Tech's could operate. Hams flock'd to where the activity was and 6 was one big Bug Lamp. Around any city, any towne for that matter, evening 6 metre AM activity was just a given. Everyone operated it- from teenagers with Sixer's and homebrews- to the big-guns with their Clegg's and high power'd amps- it was a fun band, especially when adding some summer E skip! Then came early Sideband around 50.110, and later when FM became the rage- FM on '525'-- ........we had a beacon on 6 that garnder'd QSL cards from all over the planet... oh well, you get my pixtur.
.
Then, in what seem like over night--- it was gone. Want to blame it on something ?? Blame it on the "Tech's on Ten" movement finally happening.... at least I would. But don't get me wrong! , I think it was a good idea, but it sealed poor Six's fate.
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It seems like a number of readers here lament the lack of 6 metre repeaters... though I doubt these hams have ever had to maintain such a low band system. Having recently measured the size/weight/awkwardness...etc., etc...... of duplex'r cavities- and not to mention how these cavities like to warp in less than optimum climatic conditions.... I definitely side with those that want nothing to do with them. Please forgive me if this offends anyone-- this is my personal/professional take .... I ask in my defense however: what is their advantage v.s aggrevation over higher frequency systems (except for doing what hams like to do, the fun of building stuff) ?*
.
Truthfully, I don't think six is going anywhere- either going away, or into any renaissance. It will remain a exotic ham band, coming alive briefly evey spring, like the short-lived May Fly, for the ARRL spring VHF weekend contest - a burst of SSB flurry activity- then quiet again......... Californians will be heard on 525 every now and then... someone will call "CQ" on .125..... but quiet will reign over all.
.
I just posted my experiences with a simplex repeater. I was quite taken by what its potential was-- I say potential, because that was all it had.... Nothing practical. It was very easy to construct, and if things like that were on 6 metre's it just 'might'.. a big maybe, spark some local interest in six, or your own private interests in exploring what 6 can do.... a Coyote suggestion- just a suggestion.
.
Do I have any points here??... good question !... but I enjoyed the diversion in writing this.... dinner calls...................
.
..............................................CF
.

.*I know and agree, it has better fill in varying terrain, etc-- and I like that-- but at what cost?

 

[mass-man]

Ah a goold old fashioned online discussion of 6 meters. Well, except online and old fashioned are mutually exclusive. All good points by token and CF....but i submit that the quietness of 6 doesn't fit into the operating habits of most hams! If they don't hear a net, ragchew or CW ID, then they move on.

6 meters takes patience and listening...and listening...and listening. No matter the mode, if you don't park your receiver on .125 or 52.525 or .40 and leave it there you won't know when the band opens or even a local contact can be made. I submit that a dedicated receiver for 6 is almost a necessity! You won't know what you can't hear...

Then again I spend most of my time on 6 on a couple of modes and 220FM! I must not like myself......